This invention relates to a moisture-removal device installed in a compressed air system, and in particular to a moisture-removal device having an adsorbent, which is arranged to be regenerated periodically, for removing the water and oil contained in the compressed air supplied by the air compressor.
As is known already, the air pressure equipment in a railroad car, etc., is operated by compressed air from the air compressor. This compressed air contains water and contaminants such as oil, etc., and these contaminants must be removed before the air is used. Therefore, a moisture-removal device is normally installed between the air compressor and the main air reservoir in this type of compressed air system. One example of this type of moisture-removal device is disclosed in Utility Model Kokai No. 56-2733.
This device comprises, as can be seen in FIG. 6, a flow inlet 2, a flow outlet 3 and a drain outlet 4 on one side of the main body 1. The above-mentioned flow inlet 2 is connected to the air compressor 5, and the above-mentioned flow outlet 3 is connected to the regenerating air reservoir 6. The above-mentioned drain discharge outlet 4 is connected to the discharge valve 7. The above-mentioned regenerating air reservoir 6 is connected to the air pressure equipment of the air brake system via the main air reservoir. The above-mentioned discharge valve 7 is constructed so that it connects the drain discharge outlet 4 to the atmosphere or blocks it from the atmosphere, based on the position of a switch. On the other hand, inside the main body 1, there is a cylindrical chamber 10 which consists of an inner cylinder 9 of which the bottom is opened. Inside this cylindrical chamber 10 is housed the adsorbent 11, in which the adsorbent particles are formed and fixed porously in a cylindrical form. A belt-shaped filter 12 is wound on the outer circumference of this adsorbent 11, with gaskets 13 and 14 installed on the upper end and the lower end of this belt-shaped filter 12. Each of these structural components is supported by the cap plate 16 which is fixed on the main body 1 by the bolt 15.
When the above-mentioned air compressor 5 operates, the compressed air flows to the inside of the main body 1 from the flow inlet 2, and travels along the path indicated by the arrows, to the regenerating air reservoir 6 and to the main air reservoir 8, and is stored there.
In more detail, the compressed air at the above-mentioned flow inlet 2, enters into the inner circumferential space 18 of the inner cylinder 9, via the outer circumferential path 17 and thence passing through the belt-shaped filter 12, where its oil is removed. As the air continues along its way through the adsorbent 11, water is removed and the air becomes dried compressed air. This dried compressed air passes through the inner hole 19 and through holes 20 and 21, and it moves the check valve 21 upwardly, whereupon it reaches the above-mentioned flow outlet 3, passing through the discharge path 22.
When the operation of the above-mentioned air compressor 5 is stopped, the discharge valve 7 is opened by the switching action which accompanies the operation of the air compressor, and the drain discharge outlet 4 is connected to the atmosphere, so that the compressed air in the regenerating air reservoir 6 flows back through the discharge path 22, in bypass of check valve 21, via an orifice 23, where it expands, so that it becomes drier than before. This dried air soaks up the water from adsorbent 11 by passing through the adsorbent 11 in the reverse direction, and it reaches the drain discharge outlet 4, and as a result, the adsorbent 11 is regenerated.
In the above-mentioned moisture-removal device, the belt-shaped filter 12 is wound around the outer circumference of the adsorbent 11, so that when the amount of the oil deposited on this belt-shaped filter 12 becomes excessive, the pressure difference between the inner circumference side and the outer circumference side of the belt-shaped filter 12 becomes large at the time when the compressed air is supplied (during the moisture-removal phase), and because of this pressure difference, the oil enters into the adsorbent 11, and this causes a deterioration of its capability. In addition, at the time of discharge (during the regeneration phase), the belt-shaped filter 12 becomes a barrier, and the oil inside the adsorbent 11 cannot be released to the outside, which represents a disadvantage.
Therefore, in order to eliminate these disadvantages, as can be seen in FIG. 7, the method used is one in which the oil in the belt-shaped filter 12 is prevented from entering directly into the adsorbent 11 by forming a space 24 between the outer circumference of the adsorbent 11 and the belt-shaped filter 12. In addition, as can be seen in FIG. 8, a thin pipe 12x, which is traversed by many holes, is fitted with the inner circumference of the above-mentioned belt-shaped filter 12 to form this space 24. In addition, as can be seen in FIG. 7, the mesh-shaped tube 19x, which holds the broken pieces of the adsorbent 11 when the adsorbent loses its shape, is inserted in the inner hole 19 of the adsorbent 11.
However, even with the space 24 provided between the adsorbent 11 and the belt-shaped filter 12, as mentioned above and as shown in FIG. 8, during the supply of compressed air A, the oil droplets B that are deposited on the belt-shaped filter 12, run down along the inner circumferential surface as is indicated by the arrows, and an oil puddle X is formed in the area where the lower side of gasket 14 and the lower end (sealing member 12a) of the belt-shaped filter 12 meet. This oil puddle X remains in this position during the discharge of the compressed air A' indicated in FIG. 9. Thus, when the oil puddle is formed, and if it remains like this, the oil will enter into the inside of the adsorbent 11 from the puddle X during the supply of the compressed air A, and therefore the capability of the adsorbent becomes deteriorated in the lower part, which represents a problem.